Age / Sex : 46 / F

Age / Sex : 46/F

GCT

Discussion

Findings:

1.     Radiography: eccentric, osteolytic bone lesion in the right side sacrum

2.     CT: osteolysis with soft tissue attenuation in the right side sacrum and remnant several bone fragments within the mass

3.     MRI: low signal intensity mass occupying the right sacrum on T1WI, heterogeneous low signal intensity lesion on T2WI, heterogeneous contrast enhancement of the mass on enhanced image.

4.     Bone scan: Doughnut sign including intense uptake around the peripheral with little activity in central portion

Differential Diagnosis:

Chondrosarcoma

Diagnosis: 

Giant cell tumor of the sacrum

Discussion:

1. Giant cell tumors are benign but locally aggressive neoplasms that typically affect the extremities. When involving the spine, the sacrum is the most common site. Giant cell tumor is the second most common primary sacral tumor after chordoma.

2. These neoplasms manifest as a lytic, expansile. Compared with chordomas, which are central lesions, sacral giant cell tumors are frequently eccentric and abut or extend across the sacroiliac joint.

3. On CT scans and MR images, giant cell tumors are frequently heterogeneous because of the presence of necrosis (low-attenuation areas), hemorrhage (high-signal-intensity areas on T1- and T2-weighted sequences or fluid-fluid levels), or cystic spaces. Low signal intensity is frequently noted on T2-weighted images and is related to the high hemorrhagic and fibrotic content of this tumor.

References:

Aoki et al. Giant cell tumors of bone containing large amounts of hemosiderin: MR-pathologic correlation. JCAT 1991;15:1024-1027

Imaging of sacral tumours. Gerber S et al. Skeletal Radiol. 2008;37:277-89.

Imaging of painful solitary lesions of the sacrum. Peh WC et al. Australas Radiol. 2007;51:507-15.